1. Field
The present disclosure relates generally to measuring pressure and, in particular, to measuring static pressure. Still more particularly, the present disclosure relates to a method and apparatus for improving the accuracy of static pressure measurements made using pressure taps.
2. Background
Fluid pressure is a measure of the force per unit area exerted by a fluid. The fluid may be comprised of a gas, a liquid, or a combination of the two. There are two types of fluid systems: static systems and dynamic systems. In a static system, the fluid is at rest and not moving. In a dynamic system, the fluid is moving.
In dynamic systems, fluid pressure may be expressed using three different types of pressures: static pressure, dynamic pressure, and total pressure. The static pressure of a fluid is a representation of non-directional molecular motion. Further, the static pressure of a fluid is independent of the movement of a fluid and acts equally in all directions. Dynamic pressure is generated by movement of the fluid. In particular, dynamic pressure is the kinetic energy per unit volume of a fluid particle. In other words, dynamic pressure is the portion of fluid pressure that represents the kinetic energy of a fluid. Total pressure is the sum of the static pressure and the dynamic pressure of a fluid.
Oftentimes, the static pressure of a fluid in a dynamic system is measured using pressure taps. For example, the static pressure of a fluid flowing within a fluid duct may be measured using a pressure tap located in the wall of the fluid duct. The pressure tap is typically created as a hole in the wall of the fluid duct. The location and angle of the pressure tap relative to the wall of the fluid duct is selected to reduce the effect of the flow of the fluid through the fluid duct on the static pressure measurement.
A pressure sensor may be connected to the pressure tap using, for example, a hose or tube. The pressure measured by the pressure sensor is a measurement of the static pressure of the fluid at the location of the pressure tap. However, this measurement may include bias. In other words, the measurement may not represent the true static pressure of the fluid at that location. The bias may be due to, for example, the undesired inclusion of dynamic pressure in the measurement.
Some currently available methods for reducing this bias include changing a size or shape of the pressure tap, removing burrs around the edges of the pressure tap, or moving the pressure tap to a location where the flow of the fluid has a reduced velocity. Other currently available methods may adjust for the bias after the measurements have been made.
However, these solutions may not increase the accuracy of the measurements as much as desired, may be more time-consuming than desired, may be more expensive than desired, may be more complex than desired, or some combination thereof. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.